This invention generally relates to navigation or route guidance systems and, more particularly, to a vehicle location display for a route guidance system.
Navigation systems generally provide a recommended route from a starting point to a desired destination. Generally, the starting point and desired destination are selected from a large database of roads stored in a mass media storage, such as a CD ROM or hard drive, which includes the roads in the area to be travelled by the user. The navigation system can be located in a personal computer or it can be installed in a vehicle. If the navigation system is installed in a vehicle, the starting point is typically the current position of the vehicle, which can be input to the navigation system by an associated position determining system that usually includes a GPS (Global Positioning System) receiver.
The navigation system determines a route from the starting point to the destination utilizing an algorithm well-known to those in the art and currently in use in many navigation systems. Usually there are many potential routes between the selected starting point and the desired destination. Typical navigation systems select a recommended route based upon certain "cost" values associated with each segment of road in the road database. These cost values include the length of the road segment and the estimated time of travel through the road segment. The navigation system selects the potential route with the lowest total cost to be the recommended route. Depending upon the predetermined algorithm of the navigation system, the navigation system will recommend the route with the shortest total length, the lowest total time, or some weighted average of length and time.
The recommended route is then displayed to the user as a map showing the starting point, desired destination and highlighting the recommended route. Preferably, if the navigation system is installed in a vehicle, the navigation system displays the current location of the vehicle and provides turn-by-turn instructions to the driver, guiding the driver to the selected destination.
The typical navigation system provides the current vehicle location to the user by displaying either a textual guidance mode screen having a set of instructions and the current location or a guidance mode map showing the starting point, desired destination, current location and highlighting the recommended route. When a user has not determined a route, the typical navigation system displays a map of the current vehicle location and all of the surrounding streets.
One disadvantage of the typical guidance mode map showing the current location is its complexity. Because the guidance mode map contains so much information it can be difficult for a user to rapidly view the display to confirm the current location, major surrounding roads and the next maneuver instruction. Some guidance mode map displays permit the user to select a viewing scale to aid in reducing the complexity but, this requires further input from a user while the user is enroute.
Another disadvantage of current navigation system displays is that it can be time consuming, because of the number of required keystrokes, for a user to switch between the guidance mode map display and a display of stored textual information such as an address book, emergency information, or points of interest.
Thus, it is desirable to provide a vehicle location display that automatically reduces the complexity of a displayed map and shows the current vehicle location. It is furthermore desirable to provide a vehicle location display that permits a user to access stored textual information rapidly using a minimum number of keystrokes.